Note: Descriptions are shown in the official language in which they were submitted.
740864
1
SEPARATION VESSEL WITH ENHANCED PARTICULATE REMOVAL
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of U.S. Provisional
Patent Application
Ser. No. 62/620,698, filed on January 23, 2018, which is incorporated herein
in its entirety by
this reference.
BACKGROUND OF THE DISCLOSURE
[0002] The present disclosure relates to a separation vessel for
separating gas, sediment,
and water from crude oil for oil production that contains significant amounts
of water.
[0003] With oil prices hovering around $85-$100/barrel, current economics
strongly
favor separating and selling every drop of crude oil possible. Water
production now
dominates many oilfield operations, and too much oil remains entrained in it.
The
conventional API gun barrel separator tanks are the type of separation vessels
that are often
used to try to separate that oil. Those tanks were designed to remove small
quantities of
water from large quantities of oil, not small amounts of oil from large
quantities of water.
Today's high water cuts suggest that these old industry workhorses may be
obsolete when
large volumes of water are involved.
[0004] The present invention addresses this problem with a more
sophisticated, a
more complex, and a more expensive type of separator. However, at today's oil
prices, the
initial cost of installation of this more expensive type of separator is
recovered in just a matter
of days by the direct benefit of increased oil recovery achieved by this new
separator design
over the conventional gun barrel vessels currently in use.
[0005] Also, there are other indirect cost savings associated with
disposal of water
effluent from the present invention verses disposal of water effluent from the
conventional
gun barrel vessel tanks currently in use. The oil that exits with the water
effluent from the
inefficient conventional gun barrel vessels is disposed of with the water
effluent into injection
wells or disposal wells. The oil contained in that water effluent has a
tendency to plate out on
the tubular, the well liner, the well bore and the formation rock of the
disposal well. Because
the oil is water-insoluble, as it coats the formation face, it begins to
restrict or plug the flow
of water flowing from the well to the formation. Most of the suspended solids
in the water
accumulate in this oily material, increasing the volume of the deposit and
causing even more
CA 3030856 2019-01-22
740864
2
plugging. This oily residue tends to build up in the formation within a few
feet of the well
bore and on the formation face, forming impervious flow paths that eventually
cause injection
pressures to climb and injection rates to decline.
[0006] As injection rates decline, it is common practice to stimulate the
disposal well,
often using a dilute solution of hydrochloric acid or other common stimulation
solvents,
usually with added surface active chemical ingredients. After the first
stimulation, the result
is that the well is returned to near its original injection rate and pressure.
However, it is also
common that after the first stimulation, injection rates fall off and
injection pressures increase
more rapidly than before. This situation becomes more severe after each
subsequent
stimulation effort until a point of diminishing returns is reached.
Eventually, when
stimulation efforts fail and the disposal well bore is obviously damaged
beyond reclamation,
it is then necessary to re-drill, sidetrack and recomplete the existing
disposal well, or to drill a
new disposal well. The costs for these more drastic measures range from
$500,000 to
$3,000,000. This is the indirect cost of poor water quality in the effluent
from the oil water
separators that are in use today.
[0007] With such staggering direct and indirect costs, it seems prudent to
take positive
steps to capture and sell as much of the entrained oil as possible in the
crude oil stream, and
to take steps to prevent well plugging from any and all other sources of
contaminants such as
solids, bacteria, etc.
[0008] One step is to select oil-water separation equipment that actually
separates all
physically separable oil from the produced water. The goal of the present
invention is to
provide a 20-30 fold increase in separation efficiency over conventional gun
barrel separating
tanks. Conventional gun barrel tanks will be only 3-5% hydraulically efficient
at separating
entrained oil, whereas the present invention is 60-72% hydraulically efficient
at separating
the entrained oil. The present invention reduces the oil concentration to
below 50 ppm in the
effluent water as compared to approximately 300-1500 ppm of oil in the
effluent water
emanating from conventional gun barrel separation tanks.
BRIEF SUMMARY OF THE DISCLOSURE
[0009] In one aspect, the present disclosure describes a separation tank
for separating
water and particulates from crude oil. The separation tank includes a tank
enclosing an
interior space. A central column is disposed in the tank, the central column
having a top
portion and a bottom portion, the top portion fluidly connected to an inlet
and the bottom
CA 3030856 2019-01-22
740864
3
portion fluidly connected to an outlet. The top portion is open to the
interior space of the
tank through a spiral diffuser, which includes a plurality of spiral vane
baffles disposed
adjacent to inlet fluid slots and connected along their top to a horizontal
quieting upper donut
baffle. The bottom portion is open to the interior space through at least one
outlet hole. An
oil collector weir is disposed adjacent atop of the interior space and is
fluidly connected to an
oil outlet disposed external to the tank. An upper flow diverting baffle is
located below the
spiral diffuser and a lower flow diverting baffle is provided below the upper
flow diverting
baffle so that fluid flows downward within the water section around the two
flow diverting
baffles. The upper flow diverting baffle has an outer peripheral diameter.
[0010] In one embodiment, the separation tank further includes an aerated
water
dispensing system, which comprises at least one ring shaped conduit disposed
adjacent the
lower flow diverting baffle around a section of the center column. The at
least one ring
shaped conduit includes a plurality of openings that are adapted to discharge
a stream of
aerated water into the tank interior. In one embodiment, the at least one ring
shaped conduit
has a diameter that is smaller than the outer peripheral diameter of the upper
flow diverting
baffle.
10011] In another aspect, the disclosure describes a separation tank for
separating water
from oil. The separation tank includes a tank enclosing an interior space, a
central column
disposed in the tank, the central column having a top portion and a bottom
portion, the top
portion fluidly connected to an inlet and the bottom portion fluidly connected
to an outlet,
wherein the top portion is open to the interior space of the tank through a
spiral diffuser and
the bottom portion is open to the interior space through at least one outlet
hole. An oil
collector weir is provided adjacent a top of the interior space and is fluidly
connected to an
oil outlet disposed external to the tank. An aerated water dispensing system
includes: at least
one ring shaped conduit disposed around a section of the center column, the at
least one ring
shaped conduit including a plurality of openings adapted to discharge a stream
of aerated
water into the tank interior; a pump having an inlet fluidly connected via an
inlet conduit with
the interior space of the tank and an outlet fluidly connected via an outlet
conduit with the at
least one ring shaped conduit; and a mixer having an air inlet, the mixer
connected between
the inlet conduit and the outlet conduit such that air provided through the
air inlet of the
mixer is entrained into a water stream passing through the mixer from the
outlet conduit
towards the inlet conduit.
CA 3030856 2019-01-22
740864
4
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagram of the internal components contained within a
separation
vessel.
[0013] FIG. 2 is atop view of the separation vessel of FIG. 1, showing the
arrangement
of the various internal components.
[0014] FIG. 3 is a top view showing the inlet pipe attached to the center
column in an
offset manner so that the fluid entering the center column travels in a
circular path within the
center column.
[0015] FIG. 4 is top plan view of the spiral swirl vane diffuser removed
from the vessel
of FIG. I.
[0016] FIG. 5 is a top perspective view of the spiral swirl vane diffuser
of FIG. 4.
[0017] FIG. 6 is a bottom perspective view of one of the interface draw
offs from FIG. I.
[0018] FIGS. 7 and 8 are views of an embodiment for a separation tank in
accordance
with the disclosure.
[0019] FIG. 9 is a view of an alternative embodiment for a separation tank
in accordance
with the disclosure,
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring now to the drawings and initially to FIG. 1, there is
shown a separation
vessel or tank with enhanced particulate removal 10. The tank 10 is designed
for separating
gas, water and particulates from crude oil.
[0021] When the incoming fluid contains gas, the tank 10 is provided with
an optional
degassing boot (not illustrated) to allow all free gas to separate from the
remaining liquid.
This avoids the mixing that would occur in the tank 10 if the gas was allowed
to enter with
the liquids. Also, there may be provided a degassing boot at the top of the
center column, or
on the top of the tank before the fluid enters the vessel.
[0022] The incoming production fluid enters the tank 10 through an inlet
pipe 12 into a
large diameter vertical pipe provided in the center of the tank 10 that is
referred to as the
center column 14. Referring now to FIG. 3, the inlet pipe 12 is tangentially
attached to the
center column 14 in an offset manner so that the fluid enters the center
column 14 in a
circular path to increase retention time within the center column 14, as shown
by Arrows A
and B in Figure 3.
CA 3030856 2019-01-22
740864
[0023] The center column 14 is divided into two vertical sections: the
inlet section 16 and
the outlet section 18. The inlet and outlet sections 16 and 18 are separated
by a blanking
plate 20 that is installed within the center column 14 just above a lower flow
diverting baffle
24 that is attached to the center column 14. The blanking plate 20 prevents
fluid located
within the center column 14 from passing directly between the inlet and outlet
sections 16
and 18. The inlet section 16 extends from the top 22 of the tank 10 to the
blanking plate 20.
The outlet section 18 extends from the blanking plate 20 to the bottom 26 of
the tank 10. The
blanking plate 20 is installed to divide the center column 14 so the inlet
fluid cannot flow
directly to the outlet section 18 located below.
[0024] Heavier particulates entering with the fluid into the inlet section
16 of the center
column 14 fall downward within the center column 14 to the blanking plate 20
and are
periodically removed via a center column drain 90 provided above the blanking
plate 20 or
via a solids removal system 28, such as a Tore solids removal system, that is
installed
within the center column 14 above the blanking plate 20 or by both means.
[0025] Any free gas that disengages from the remaining fluid flows upward
within the
center column 14 and exits the center column 14 via gas holes 30 provided in
the top 32 of
the center column 14 and enters into a gas layer 34 located at the top 22 of
the tank 10 above
the gas-oil interface 37. Excess gas is removed from the tank 10 via a gas
vent 35 provided
in the top 22 of the tank which is in communication with the gas layer 34
within the tank 10.
Although not illustrated, there may be a degassing boot at the top 32 of the
center column 14
or on the top 22 of the tank 10.
[0026] The fluid flows out of the center column 14 via a spiral swirl vane
diffuser 36
installed in the center column 14. The spiral swirl vane diffuser 36 is
provided with vertical
curved or swirl vane baffles 38. The vertical curved or swirl vane baffles 38
will hereafter
be referred to as inlet diverters 38. Each inlet diverter is secured between a
horizontal
quieting lower donut baffle 40 and a horizontal quieting upper donut baffle
42, with adjacent
inlet diverters 38 spaced apart from each other. Inlet fluid slots 44 are
provided in the spiral
swirl vane diffuser 36 between adjacent inlet diverters 38. The inlet fluid
slots 44
communicate with the inlet section 16 of the center column 14 to allow fluid
to flow out of
the center column 14 between the inlet diverters 38 and into the interior of
the tank 10.
[0027] Referring now to FIGS. 1, 4 and 5, the inlet diverters 38 serve to
swirl the fluid as
it flows out between them. As the fluid exits the center column 14, it turns
from a vertical
upward direction, as shown by Arrow C, within the center column 14 to a
spiraling,
CA 3030856 2019-01-22
740864
6
horizontal outward direction, as shown by Arrows D, as it exits the center
column 14 through
the spiral swirl vane diffuser 36 to enter a primary separation zone 46 within
the tank 10.
[0028] The spiral swirl vane diffuser 36 distributes the fluid within the
tank 10 just below
the oil-water interface 48 through the diffuser's inlet diverters 38. These
inlet diverters 38
are curved to impart a centrifugal force on the liquids, spinning them outward
from the center
of the tank 10 in an ever increasing radius spiral, as shown by Arrows D. This
slows the
velocity of the inlet fluid and increases its effective separation time in the
primary separation
zone 46 just below the oil-water interface 48. As the inlet fluid stream
slows, smaller and
smaller droplets of oil separate and rise the short distance to the oil layer
50.
[0029] Some oil droplets accumulate on the top 52 of the large area upper
flow diverting
baffle 54 which serves also as a huge surface area coalescer. The upper flow
diverting baffle
54 is convex on its upper side or top 52 and is concave on its opposite lower
side or bottom
56. As the fluid stream spirals outward away from the center of the tank 10,
it encounters the
interior tank wall 58 that serves as another large area coalescer. Any
droplets of oil attaching
themselves to these coalescing surfaces 52 and 58 are no longer in the water,
and are now
permanently separated from the water. As these surfaces become totally coated
with oil, the
oil wicks upward, eventually entering the oil layer 50 above, adding to the
volume of oil
collected in the oil layer 50.
[0030] The oil layer 50 is designed to provide adequate time for all
accumulating oil to
completely dehydrate to typical pipeline specification or better. Uniform oil
collection is
critical to this function. A very large, concave, circular oil collector 60
provided in the center
62 of the tank 10 at the top 64 of the liquid oil layer 50 assures all oil
rises uniformly through
the entire oil layer 50, and is collected around 360 degrees of that layer 50.
The upper edge
66 of the large oil collector 60 is designed to serve as a very large
spillover oil weir 68 for oil.
Oil from the oil layer 50 that passes over the oil weir 68 and into the oil
collector 60 exits the
oil collector 60 and the tank 10 via an oil outlet 70 that is attached to the
oil collector 60.
[0031] The oil weir 68 is tall. Its height insures a minimum level
deviation even during
periods of very high incoming fluid slug rates. The level differential between
the oil outlet
70 and a downstream tank assures that large flow rates of oil can flow out of
the tank's oil
collector 60 and oil outlet 70 during slug flow conditions. Because of this,
it is nearly
impossible to overflow oil from the tank 10.
[0032] Once the bulk oil has separated from the main flow of inlet water,
the water must
turn 90 degrees downward, as shown by Arrow E, to flow down between the upper
flow
CA 3030856 2019-01-22
740864
7
diverting baffle 54 and the tank wall 58. This causes a small measure of
acceleration. As the
downward flowing water reaches the outer edge 72 of the upper flow diverting
baffle 54, it
enters a quadrant of the tank 10 which is open to full diameter flow. The
acceleration
velocity creates a mild eddy current that pulls a portion of the water in and
under the upper
flow diverting baffle 54. At this point, all fluid flow changes to vertically
downward, as
shown by Arrow F, through the entire cross sectional area of the tank 10.
Velocity is now at
its slowest, allowing the smallest of oil droplets to counter flow upward.
These droplets rise,
coating the concave bottom 56 of the upper flow diverting baffle 54. Once the
bottom 56 is
coated, the oil can migrate directly into the oil layer located above through
a pipe or oil
conduit 74 that extends from the bottom 56 of the upper flow diverting baffle
54 up into the
oil layer 50 located just below the oil collector 60, thus preventing re-
entrainment of oil in the
water layer 76. This adds even more to the volume of oil collected and to the
separation
efficiency of the tank 10.
[0033] As the clarified water travels downward and nears the bottom 26 of
the tank 10, it
encounters the lower flow diverting baffle 24 which is a second large area on
which oil can
condense. Like the upper flow diverting baffle 54, the lower flow diverting
baffle 24 is
convex on its upper side or top 78 and is concave on its lower side or bottom
80. As the
downward flowing water impinges on the top 78 of this lower flow diverting
baffle 24, oil
droplets accumulate on its top 78, further enhancing separation. Additionally,
as shown by
Arrow G, this lower flow diverting baffle 24 forces the flow stream to change
directions from
vertically downward to nearly horizontal again as the fluid turns to flow
around the lower
flow diverting baffle 24.
[0034] Now the water is flowing straight toward the inside surface or wall
58 of the tank
again. As it contacts the tank wall 58, some of the smallest oil droplets
impinge on the
tank wall 58, coating the wall 58 and are wicked up into the oil layer 50
above. Once again,
separation efficiency is enhanced.
[0035] In order to exit the tank 10, as shown by Arrow H, the water must
turn downward
again to flow between the outer edge 82 of the lower flow diverting baffle 24
and the tank
wall 58. Since this area is a fraction of the tank cross section, the water
must again increase
in velocity as it turns downward. Any solids in the water at this point are
now aimed directly
at, and are being propelled directly toward, the bottom 26 of the tank 10.
[0036] As shown by Arrow J, when the water reaches the outer edge 82 of
the lower flow
diverting baffle 24 it must turn upward more than 90 degrees and flow upward
under the
CA 3030856 2019-01-22
740864
8
concave bottom 80 of the lower flow diverting baffle 24. As the solids are
heavier than
water, they are less inclined to follow the water flow upwardly and thus
separate from the
water flow and settle to the bottom of the tank 10. The water flows along the
bottom 80 of
the lower flow diverting baffle 24 where the tiniest droplets of oil have
another chance to
coalesce and attach to the very large surface of the bottom 80. Oil
accumulating on the
bottom 80 of the lower flow diverting baffle 24 is allowed to exit through oil-
dedicated weep
holes 84 provided extending through the top 78 of the lower flow diverting
baffle 24. That
oil exits to the area under the upper flow diverting baffle 54, migrates
upward until it contacts
the bottom 56 of the upper flow diverting baffle 54 and then flows through the
oil conduit 74
directly into the oil layer 50.
[0037] The water flowing under the lower flow diverting baffle 24 now
reaches the center
62 of the tank 10 and enters the outlet section 18 of the center column 14 via
outlet holes 86.
The outlet holes are provided in the center column 14 just below the blanking
plate 20 and
below the lower flow diverting baffle 24. As shown by Arrow K, once the water
enters the
center column 14 through the outlet holes 86, it turns downward and flows down
within the
center column 14. As shown by Arrow L, from the center column14, the water
then turns
horizontally to enter a horizontal water outlet pipe 88 which directs the
water out of the tank
and into an adjustable height water leg that serves to regulate the height of
the oil-water
interface 48 located within the tank 10.
[0038] Referring to FIGS. 1 and 2, the separation tank 10 is fitted with
two internal tank
drains. The first internal tank drain is the center column drain 90 that is
located near the
solids removal system 28. The second internal tank drain is the set of
interface draw offs 92.
[0039] The center column drain 90 is the first internal tank drain.
Incoming fluid
entering the tank 10 often contains some solids. These solids will accumulate
preferentially
above the blanking plate 20. The center column drain 90 is provided so the
operator can
drain this area. It should be drained frequently until the water leaving the
drain 90 runs clear.
[0040] In order to drain the solids that accumulate above the blanking
plate 20, it may
also be desirable, in addition to the center column drain 90, to include a
solids removal
system 28, such as the Tore solids removal system 28 to aid the center column
drain 90 in
removing solids from the inlet section 16 of the center column 14. A Tore
solids removal
system 28 is a solids hydro-transportation device that utilizes the natural
power of a motive
fluid, such as water, to mobilize and transport solids, liquids or slurries.
Tore systems 28
are available from PDL Solutions Ltd. located in the United Kingdom. The Tore
solids
CA 3030856 2019-01-22
740864
9
removal system 28 includes a water inlet 94 that feeds water to the Tore
solids removal
system 28 and a water and solids outlet 91 that drains a mixture of water and
solids out of the
inlet section 16 of the center column 14.
[0041] Referring also to FIG. 6, the interface draw offs 92 collectively
constitute the
second internal tank drain. As oil accumulates in the tank 10, it is common
that some BS&W
(basic sediment and water, which is also referred to as "emulsion") will
accumulate
immediately below or at the oil¨water interface 48. The BS&W is heavier than
pure oil
because of the water and solids contained in it. Therefore, the emulsion will
build downward
from the level of the normal oil-water interface 48. Several interface draw
offs 92 are
provided in the tank 10 about a foot below the normal oil-water interface 48.
Each interface
draw offs 92 is constructed of an upper round horizontal draw off baffle 96
and a lower round
horizontal draw off baffle 98, with each draw off baffle 96 and 98 being
approximately 24
inch in diameter. The upper draw off baffle 96 is stacked on top of the lower
draw off baffle
98 of each interface draw off 92 and the two draw off baffles 96 and 98 are
spaced
approximately 4 inches apart. The area between the upper and lower draw off
baffles 96 and
98 is open to the interior 100 of the tank 10. A draw off pipe 102 is
connected to each of the
lower draw off baffles 98, and the individual draw off pipes 102 are connected
together and
piped to a convenient elevation near the bottom of the tank 10 where the pipe
exits the tank
as the BS&W interface drain 104. A BS&W valve (not illustrated) is installed
to open and
close the BS&W interface drain 104. When the BS&W valve on the BS&W interface
drain
104 is opened, the BS&W layer flows horizontally between the upper and lower
draw off
baffles 96 and 98 of each interface draw off 92 and out of the tank 10 through
the BS&W
interface drain 104. When either clean water or clean oil is observed in the
sample of the
outlet fluid, the BS&W has been removed and the BS&W valve can then be closed.
[0042] The upper and lower flow diverting baffles 54 and 24 and the
interface draw offs
92 are supported within the tank 10 by support legs 106 that extend down to
the bottom 26 of
the tank 10.
[0043] The tank 10 is provided with a cleanout man way 108 for providing
access to the
interior 100 of the tank 10 when it is out of service and also a heater man
way 110 for
installation of an immersion heater (not illustrated) within the tank 10.
[0044] Although not specifically illustrated, sand removal systems can also
be included in
the bottom of the tank 10. These should be drained daily until clean water is
observed.
CA 3030856 2019-01-22
740864
[0045] Although not illustrated, a water leg will be installed on site with
the tank 10 as a
means of regulating the fluid levels. The water leg is a pipe within a pipe.
The clarified
water enters through the outer pipe and turns upward where it flows in the
annular space
between the two pipes. The inner pipe is sized for its circumference. The
circumference of
the outer pipe forms a spillover weir for the water with the inner pipe. The
height of the top
of the inner pipe establishes the weir that sets the level of the oil-water
interface 48 inside the
separation tank 10. The height of this weir is critical. It is always
adjustable, either by
removing an upper removable center pipe nipple, or via an external adjustment
assembly that
slides a movable upper section of the inner pipe up and down to change its
spillover
elevation.
[0046] An alternative embodiment of a tank 200 is shown in FIG. 7, and a
variation of the
tank 200 is shown in FIG. 9. In the description that follows, certain
structures and features
that are the same or similar to corresponding structures and features
previously described are
denoted by the same reference numerals previously used for simplicity. The
tank 200
includes a tank wall 202 that encloses an internal tank space 204. The tank
wall 202 includes
a circular floor 206, a cylindrical sidewall 208 and a domed cap 210, each of
which may
include various openings for the passage of fluids therethrough, as required.
[0047] The tank 200 is generally structured similar to the tank 10 with a
few notable
differences. For example, the inlet diverters 38 that surround the inlet fluid
slots 44 are
engaged along their top with the horizontal quieting upper donut baffle 42 but
the lower
donut baffle 40 of tank 10 has been removed in tank 200 such that inlet fluid
and,
specifically, the water included therewith, begins sinking towards the bottom
along the top
surface of the upper flow diverting baffle 54 immediately upon discharge of
the inlet fluid
slots 44 of the center column 14. Also, a gas outlet 400 fluidly communicates
with the top of
the tank interior.
[0048] Additionally, the tank 200 includes an aerated water dispensing
system 220,
which enhances the separation efficiency of the tank 200 as compared to the
tank 10 by
providing aerated water under pressure into the internal tank space 204. The
air diluted in the
aerated water thus provided creates micro bubbles that can attach to oil
droplets that are 30
microns or less and are mixed with the water in the lower portions of the
interior tank space
204. These air bubbles, which use the oil droplets as germination sites to
form from the air-
saturated water, attach themselves to the oil droplets and thus increase the
buoyancy of these
CA 3030856 2019-01-22
740864
11
small oil droplets and carry them towards the top of the internal tank space
and into the oil
layer 50.
[0049] In the embodiment illustrated in FIG. 7, the aerated water
dispensing system 220
draws water from the tank 200, adds air into the water drawn, and provides the
aerated water
back into the tank to help extract fine oil droplets from the water, as
described above. In the
variation shown in FIG. 9, the aerated water dispensing system 220 can
selectively draw
controllable portions of air and/or gas from the top of the tank, which is
added to the water
drawn and provided back in the tank. More particularly, and in further
reference to the
enlarged detail view of FIG. 8, the aerated water dispensing system 220
includes a pump 222
having an inlet 224 that is fluidly in communication with an inlet port 226 of
the tank
sidewall 208 via an inlet conduit 228. The inlet port 226 is located at a
height above the
bottom 206 of the tank to discourage ingestion of sand in the pump 222 during
operation.
The pump 222, which may be operated by an electric motor (not shown) or
another
appropriate motive source, draws a flow of water from the tank 200 through the
inlet conduit
228 during operation, pressurizes the water, and provides pressurized water at
a pump outlet
230. The pump outlet 230 is connected to an outlet conduit 232, which may also
include a
pressure monitor 234.
[0050] During operation, a pressure difference is provided across the pump
inlet and
outlet 224 and 230, which is also present across the inlet and outlet conduits
228 and 232.
This pressure difference, in the illustrated embodiment, is used to draw a
flow of air and mix
it with the flow of water, but other arrangements can be used. As shown in
FIGS. 7 and 8, a
mixing conduit includes a mixer 236, which operates on a venturi principle to
introduce or
entrain a controlled amount of air into a flow of water passing through a
central portion of the
mixer 236. The airflow into the mixer 236 is controlled and measured by a
rotameter 238. In
the embodiment of FIG. 7, the rotameter 238 is the only input to the mixer
236. In the
embodiment of FIG. 9, a second rotameter 402 can selectively also provide gas
from the tank
interior to the mixer 236. As shown in FIG. 9, the second rotameter 402 is
fluidly connected
to the tank interior through the gas outlet 400, via a gas line 404. As the
mixer 236
introduces air and/or gas into the water at the inlet conduit 228, the air,
gas, or a mixture of
air and gas is premixed with the water flow at the mixer and also as the air
and/or gas and
water together pass through the pump 222. The premixed air air/or gas and
water provided at
the outlet conduit 232 may also pass through a pressure regulator and are
routed into a
CA 3030856 2019-01-22
740864
12
pressurized canister 240 for further mixing of the air/gas and water into an
air/gas saturated
water flow.
[0051] In the illustrated embodiment, the canister 240 is filled with media
that operates to
mix the air/gas and water. As shown, the canister 240 is disposed within the
tank, although
external mounting is also contemplated, and is filled with ceramic saddles
242. During
operation, water and air/gas from the outlet conduit 232 are provided through
the top of the
canister 240 and pass therethrough in a downward direction along a tortious
path that dilutes
the air and/or gas into the water to form an aerated water mixture. The amount
of air/gas
introduced into the water may be selected to be at or below an air/gas
saturation point for the
water at the then current temperature and pressure.
[0052] The aerated water flow exits the canister 240 through its bottom and
is routed
through an aerated water supply conduit 244, which also includes a valve 246
such as a
diaphragm valve 246, into a distribution network 247 disposed within the tank.
The aerated
water will depressurize when introduced into the tank environment and will
spawn bubble
formation that will capture fine oil droplets and raise them towards the top
of the tank. For
this reason, the aerated water is introduced towards the bottom of the tank.
In the illustrated
embodiment, the distribution network includes perforated pipes attached to the
lower
diverting baffle 24. As shown, two ring-shaped conduits 248 are disposed
peripherally
around certain sections of the lower diverting baffle 24. An upper conduit 248
is disposed
along the apex of the upper, convex surface of the lower diverting baffle 24,
around the
center column 14. A lower conduit 248 is disposed along an outer periphery of
the upper,
convex surface of the lower diverting baffle 24. Each conduit 248 includes one
or more
openings 250 that allow aerated water from within the conduit 248 to be
introduced into the
internal tank space 204. Fewer or more than two conduits 248 may be used. The
aerated
water is provided as a discharge 252 into the tank interior 204.
[0053] While the invention has been described with a certain degree of
particularity, it is
manifest that many changes may be made in the details of construction and the
arrangement
of components without departing from the spirit and scope of this disclosure.
It is understood
that the invention is not limited to the embodiments set forth herein for the
purposes of
exemplification, but is to be limited only by the scope of the attached claim
or claims,
including the full range of equivalency to which each element thereof is
entitled.
[0054] All references, including publications, patent applications, and
patents, cited
herein are hereby incorporated by reference to the same extent as if each
reference were
CA 3030856 2019-01-22
740864
13
individually and specifically indicated to be incorporated by reference and
were set forth in
its entirety herein.
[0055] The use of the terms "a" and "an" and "the" and "at least one" and
similar
referents in the context of describing the invention (especially in the
context of the following
claims) are to be construed to cover both the singular and the plural, unless
otherwise
indicated herein or clearly contradicted by context. The use of the term "at
least one"
followed by a list of one or more items (for example, "at least one of A and
B") is to be
construed to mean one item selected from the listed items (A or B) or any
combination of two
or more of the listed items (A and B), unless otherwise indicated herein or
clearly
contradicted by context. The terms "comprising," "having," "including," and
"containing"
are to be construed as open-ended terms (i.e., meaning "including, but not
limited to,") unless
otherwise noted. Recitation of ranges of values herein are merely intended to
serve as a
shorthand method of referring individually to each separate value falling
within the range,
unless otherwise indicated herein, and each separate value is incorporated
into the
specification as if it were individually recited herein. All methods described
herein can be
performed in any suitable order unless otherwise indicated herein or otherwise
clearly
contradicted by context. The use of any and all examples, or exemplary
language (e.g., "such
as") provided herein, is intended merely to better illuminate the invention
and does not pose a
limitation on the scope of the invention unless otherwise claimed. No language
in the
specification should be construed as indicating any non-claimed element as
essential to the
practice of the invention.
[0056] Preferred embodiments of this invention are described herein,
including the best
mode known to the inventors for carrying out the invention. Variations of
those preferred
embodiments may become apparent to those of ordinary skill in the art upon
reading the
foregoing description. The inventors expect skilled artisans to employ such
variations as
appropriate, and the inventors intend for the invention to be practiced
otherwise than as
specifically described herein. Accordingly, this invention includes all
modifications and
equivalents of the subject matter recited in the claims appended hereto as
permitted by
applicable law. Moreover, any combination of the above-described elements in
all possible
variations thereof is encompassed by the invention unless otherwise indicated
herein or
otherwise clearly contradicted by context.
CA 3030856 2019-01-22
